dt-bindings: serial: snps-dw-apb-uart: Add support for rk3562

dt-bindings: serial: snps-dw-apb-uart: Add support for rk3562

The UART core on Rockchip's RK3562 is the same as the one already
included in generic dw-apb-uart. Extend the binding accordingly to allow

	compatible = "rockchip,rk3562-uart", "snps,dw-apb-uart";

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20250227111913.2344207-9-kever.yang@rock-chips.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>